JP5593984B2 - Secondary battery current collector - Google Patents

Description

  The present invention relates to a current collector for a secondary battery and a secondary battery using the current collector.

  In recent years, hybrid vehicles (HEV), electric vehicles (EV), and fuel cell vehicles have been manufactured and sold from the viewpoint of environment and fuel consumption, and new developments are continuing. In these so-called electric vehicles, it is indispensable to use a power supply device capable of discharging and charging. As the power supply device, a secondary battery such as a lithium ion battery or a nickel metal hydride battery, an electric double layer capacitor, or the like is used. In particular, lithium ion secondary batteries are considered suitable for electric vehicles because of their high energy density and high durability against repeated charging and discharging, and various developments have been intensively advanced. However, in order to apply to the power sources for driving motors of various automobiles as described above, it is necessary to use a plurality of secondary batteries connected in series in order to ensure a large output.

  However, when a battery is connected via the connection portion, the output is reduced due to the electrical resistance of the connection portion. Further, the battery having the connection portion has a disadvantage in terms of space. That is, the connection portion causes a reduction in the output density and energy density of the battery.

  In order to solve this problem, bipolar secondary batteries such as bipolar lithium ion secondary batteries have been developed. A bipolar secondary battery has a structure in which a plurality of bipolar electrodes, each having a positive electrode active material layer formed on one side of a current collector and a negative electrode active material layer formed on the other side, are stacked via an electrolyte layer or a separator. Have

  The current collector used in such a bipolar secondary battery is preferably made of a material that is lighter and more conductive in order to ensure a higher output density. Therefore, in recent years, a current collector composed of a polymer material to which a conductive material is added instead of a conventional metal foil has been proposed. For example, Patent Document 1 discloses a current collector containing a conductive resin in which metal particles or carbon particles are mixed as a conductive material in a polymer material.

JP 2006-190649 A

  However, the current collector as described in Patent Document 1 has a lower barrier property against lithium ions in the electrolytic solution than the metal foil current collector. For this reason, when applied to a bipolar lithium ion secondary battery, lithium ions may penetrate into the current collector of the bipolar electrode and the lithium ions may remain occluded inside the current collector. It was. Since the occluded lithium ions are not easily released, the capacity of the battery may be reduced.

  Therefore, an object of the present invention is to provide means for suppressing the occlusion of lithium ions into the current collector in a current collector for a bipolar secondary battery including a conductive resin layer.

  The inventors of the present invention have made extensive studies in view of the above problems. As a result, in a current collector for a secondary battery including a conductive resin layer, an ion blocking layer including a flat conductive filler whose long side direction is arranged in the surface direction of the resin layer is formed on the resin layer. It has been found that the above object can be achieved by disposing on the surface.

  According to the present invention, since lithium ions need to reach between the flat conductive fillers and reach the resin layer, the penetration of lithium ions into the resin layer can be suppressed.

1 is a schematic cross-sectional view schematically showing a secondary battery current collector according to an embodiment of the present invention. 1 is a schematic cross-sectional view schematically showing a secondary battery current collector according to an embodiment of the present invention. 1 is a schematic cross-sectional view schematically showing a secondary battery current collector according to an embodiment of the present invention. It is a schematic sectional drawing showing the bipolar electrode using the electrical power collector by one Embodiment of this invention. It is a schematic sectional drawing showing the structure of a bipolar lithium ion secondary battery.

  Hereinafter, preferred embodiments of the present invention will be described. The present embodiment relates to a current collector for a secondary battery including a conductive resin layer and an ion blocking layer arranged on the surface of the resin layer. The ion blocking layer includes a flat conductive filler, and a long side direction of the flat conductive filler is arranged in a surface direction of the resin layer.

  Hereinafter, the present embodiment will be described with reference to the accompanying drawings. However, the technical scope of the present invention should be determined based on the description of the scope of claims, and is not limited to the following embodiments. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted. In addition, the dimensional ratios in the drawings are exaggerated for convenience of explanation, and may be different from the actual ratios.

<Current collector>
The current collector has a function of mediating the movement of electrons from one surface on which the positive electrode active material layer is formed to the other surface on which the negative electrode active material layer is formed. The current collector according to the present embodiment includes a conductive resin layer (hereinafter also simply referred to as “resin layer”) and an ion blocking layer disposed on the surface of the conductive resin layer.

  Fig.1 (a) is sectional drawing which represented typically the collector for secondary batteries which concerns on one Embodiment of this invention. A current collector 11 of the present embodiment shown in FIG. 1A includes a conductive resin layer 2 and an ion blocking layer 3 disposed on the surface of the conductive resin layer 2. The ion blocking layer 3 includes a plurality of flat conductive fillers 4, and the long side direction of the flat conductive fillers 4 is arranged and deposited in the surface direction of the resin layer 2 having conductivity.

  Here, “disposed on the surface of the resin layer having conductivity” means any of the case where it is disposed in contact with the surface of the resin layer 2 having conductivity and the case where it is disposed via another material. Is also included. The ion blocking layer 3 may be disposed so as to cover the entire surface of the resin layer 2 having conductivity, or may be configured to cover a part of the surface. The ion blocking layer 3 may be disposed on one surface of the resin layer 2 having conductivity, or may be disposed on both surfaces.

  Hereinafter, the resin layer and the ion blocking layer constituting the current collector of the present embodiment will be described.

(Conductive resin layer)
The conductive resin layer has a function as an electron transfer medium, and can contribute to reducing the weight of the current collector. The resin layer may include a base material made of a polymer material, and if necessary, a conductive filler and other members.

  There is no restriction | limiting in particular in resin used for a base material, A conventionally well-known nonelectroconductive polymer material or a conductive polymer material can be used without a restriction | limiting. Preferred non-conductive polymer materials include, for example, polyethylene (PE; high density polyethylene (HDPE), low density polyethylene (LDPE)), polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), poly Ether nitrile (PEN), polyimide (PI), polyamideimide (PAI), polyamide (PA), polytetrafluoroethylene (PTFE), styrene-butadiene rubber (SBR), polyacrylonitrile (PAN), polymethyl acrylate (PMA) , Polymethyl methacrylate (PMMA), polyvinyl chloride (PVC), polyvinylidene fluoride (PVDF), polystyrene (PS), silicone resin, cellulose, and epoxy resin. Such a non-conductive polymer material may have excellent potential resistance or solvent resistance. Examples of preferable conductive polymer materials include polyaniline, polypyrrole, polythiophene, polyacetylene, polyparaphenylene, polyphenylene vinylene, polyacrylonitrile, and polyoxadiazole. Since such a conductive polymer material has sufficient conductivity without adding a conductive filler, it is advantageous in terms of facilitating the manufacturing process or reducing the weight of the current collector. These non-conductive polymer materials or conductive polymer materials may be used alone or in a combination of two or more.

  A conductive filler may be added to the conductive polymer material or the non-conductive polymer material as necessary. In particular, when the resin used as the base material of the current collector is made of only a non-conductive polymer, a conductive filler is inevitably necessary to impart conductivity to the resin. The conductive filler can be used without particular limitation as long as it is a substance having conductivity. For example, metals, alloys, metal oxides, conductive carbon, and the like can be given as materials having excellent conductivity, potential resistance, or lithium ion blocking properties.

  The metal is not particularly limited, but includes at least one metal selected from the group consisting of Ni, Ti, Al, Cu, Pt, Fe, Cr, Sn, Zn, In, Sb, and K. preferable. An alloy or metal oxide containing these metals can also be preferably used. These metals are resistant to the potential of the positive electrode or negative electrode formed on the current collector surface. Among these, an alloy containing at least one metal selected from the group consisting of Ni, Ti, Al, Cu, Pt, Fe, and Cr is more preferable.

  Specific examples of the alloy include stainless steel (SUS), Inconel (registered trademark), Hastelloy (registered trademark), and other Fe—Cr alloys, Ni—Cr alloys, and the like. By using these alloys, higher potential resistance can be obtained.

  The conductive carbon is not particularly limited, but is at least selected from the group consisting of acetylene black, vulcan, black pearl, carbon nanofiber, ketjen black, carbon nanotube, carbon nanohorn, carbon nanoballoon, and fullerene. It is preferable that 1 type is included. These conductive carbons have a very wide potential window, are stable in a wide range with respect to both the positive electrode potential and the negative electrode potential, and have excellent conductivity. Further, since the density is lower than that of the conductive filler containing the above metal, the current collector can be reduced in weight. Among these, it is more preferable to include at least one selected from the group consisting of carbon nanotubes, carbon nanohorns, ketjen black, carbon nanoballoons, and fullerenes. Since these conductive carbons have a hollow structure, the surface area per mass is large, and the current collector can be further reduced in weight. In addition, electroconductive fillers, such as these metals and electroconductive carbon, can be used individually by 1 type or in combination of 2 or more types.

  The size of the conductive filler is not particularly limited, and fillers of various sizes can be used depending on the size and thickness of the resin layer or the shape of the conductive filler. As an example, the average particle diameter when the conductive filler is granular is preferably about 0.1 to 10 μm from the viewpoint of facilitating molding of the resin layer. In the present specification, “particle diameter” means the maximum distance L among the distances between any two points on the contour line of the conductive filler. As the value of “average particle diameter”, the average particle diameter of particles observed in several to several tens of fields using an observation means such as a scanning electron microscope (SEM) or a transmission electron microscope (TEM). The calculated value shall be adopted. The particle diameter and average particle diameter of an active material to be described later can be defined similarly.

The content of the conductive filler contained in the resin layer is not particularly limited. In particular, when the resin includes a conductive polymer material and sufficient conductivity can be secured, it is not always necessary to add a conductive filler. However, when the resin is made of only a nonconductive polymer material, it is essential to add a conductive filler in order to impart conductivity. In this case, the content of the conductive filler is preferably 5 to 35% by mass, more preferably 5 to 25% by mass, and further preferably 5 to 5% by mass with respect to the total mass of the non-conductive polymer material. 15% by mass. By adding such an amount of conductive filler to the resin, sufficient conductivity can be imparted to the non-conductive polymer material while suppressing an increase in the mass of the resin layer.

  There is no restriction | limiting in particular in the shape of an electroconductive filler, Well-known shapes, such as a granular form, fibrous form, plate shape, flat shape, lump shape, cloth shape, and mesh shape, can be selected suitably. For example, when it is desired to impart conductivity to a resin over a wide range, it is preferable to use a granular conductive filler. On the other hand, when it is desired to further improve the conductivity in a specific direction in the resin, it is preferable to use a conductive filler having a certain direction in the shape of a fiber or the like.

  The thickness of the conductive resin layer is preferably thin in order to increase the output density of the battery by reducing the weight. Specifically, the thickness of one conductive resin layer is preferably 0.1 to 200 μm, more preferably 5 to 150 μm, and even more preferably 10 to 100 μm. .

(Ion blocking layer)
The ion blocking layer 3 is made of a material having a property of suppressing permeation of ions or a solvent in the electrolyte. Here, the permeation of the solvent is mentioned because the movement of ions occurs using the solvent in the electrolyte as a medium, so that the permeation of ions can be indirectly suppressed by suppressing the permeation of the solvent. is there.

  As shown in FIG. 1A, in the current collector 11 of the present embodiment, the ion blocking layer 3 includes a flat conductive filler 4 disposed along the surface direction of the resin layer 2 having conductivity. It is characterized by including. This causes a labyrinth effect and suppresses permeation of the electrolyte and lithium ions. As a result, a reduction in battery capacity due to occlusion of lithium ions in the current collector can be suppressed. Furthermore, by electrically connecting the resin layer 2 having conductivity with the ion blocking layer 3, the resistance in the thickness direction of the current collector can be reduced. Therefore, the cycle life of the battery can be improved particularly by using it for a bipolar secondary battery.

  Conventionally, when a current collector containing a conductive resin layer is used, an ion blocking layer formed of a metal foil such as a copper foil is used as a method for preventing lithium ions in the electrolyte from permeating through the resin layer. A method of bonding and laminating on the surface of a conductive resin layer has been used. However, using a metal foil leads to an increase in weight as a current collector, and the battery capacity per unit weight can be reduced. Moreover, since metal foil is hard to adhere | attach with resin, when electrolyte solution osmose | permeates the interface of the resin layer and metal foil which have electroconductivity, adhesiveness may fall and metal foil may peel. In particular, when the metal foil is thinned in order to reduce the weight, pinholes are generated in the metal foil, and the adhesiveness with the resin layer tends to be lowered. Furthermore, since the connection resistance between the resin layer and the metal foil is large, the resistance in the thickness direction of the current collector is increased. As a result, the current collection efficiency of the current collector is lowered, and the battery performance can be lowered. .

  On the other hand, the current collector 11 of the present embodiment includes a flat conductive filler (first conductive filler) 4, and the long side direction of the flat conductive filler 4 has the conductivity. 2 having an ion blocking layer disposed in the plane direction. The ion blocking layer using the conductive filler as described above has higher adhesion to the resin layer than the metal foil. Therefore, as compared with the case where a metal foil is used, a sufficient lithium ion blocking effect can be obtained even with a thin layer. This is advantageous from the viewpoint of weight reduction and suppressing increase in resistance in the thickness direction of the current collector. Further, by electrically connecting the conductive resin layer with the ion blocking layer, the resistance in the thickness direction of the current collector (surface resistance) can be further reduced.

  Furthermore, when the flat conductive filler 4 is used while being arranged along the surface direction of the resin layer 2 whose long side direction is conductive, a maze effect is generated. That is, it is necessary for lithium ions to reach between the flat conductive filler 4 and reach the conductive resin layer 2. Therefore, permeation of the electrolytic solution and lithium ions can be suppressed as compared with the case where a conductive filler having an isotropic or needle shape is used. Therefore, occlusion of lithium ions into the resin layer can be suppressed.

  In this specification, “flat” means, for example, the shape of a particle having a large size in the other two directions with respect to the size in one direction in the three dimensions, as in the shape shown in FIG. is there. Here, the direction in which the distance between any two points on the particle outline is maximum is the long side, the size is a, the direction perpendicular to the long side direction and the shortest distance is the thickness, the size is t, When the direction perpendicular to these is the short side and the size is b, the shape in which the value of a / b is 2 or more is defined as “flat”. The flat conductive filler has a long side, a short side, and a thickness of several to several tens of fields using observation means such as a scanning electron microscope (SEM) or a transmission electron microscope (TEM). The value calculated as the average value of the particle diameters of the observed particles is adopted.

  Moreover, in this specification, "the long side direction is arranged in the surface direction of the resin layer having conductivity" means that the long side direction of the flat conductive filler 4 and the surface of the resin layer 2 are It means that the average value of the angle (a) is 0 to ± 45 ° (FIG. 1 (c)). Here, when the long side direction of the flat conductive filler 4 and the surface of the resin layer 2 are parallel, the angle formed by the long side direction of the flat conductive filler and the resin layer is 0 °. The case where the long side direction of the conductive filler is perpendicular to the surface of the resin layer is defined as ± 90 °.

  The material of the flat conductive filler (first conductive filler) 4 is not particularly limited, and the same material as the conductive filler contained in the conductive resin layer can be used. Preferably, the flat conductive filler is selected from the group consisting of metals, alloys, metal carbides, metal nitrides, metal oxides, metal borides, metal sulfides, diamond-like carbon, glassy carbon, and ceramics. At least one kind. These materials have electrical conductivity, do not easily react with lithium, and have excellent ion blocking properties.

The metal is not particularly limited, but includes at least one metal selected from the group consisting of Ni, Ti, Al, Cu, Pt, Fe, Cr, Sn, Zn, In, Sb, and K. preferable. Alloys or metal carbides, metal nitrides, metal oxides, metal borides and metal sulfides containing these metals can also be preferably used. These metals are resistant to the potential of the positive electrode or negative electrode formed on the current collector surface. Of these, a metal nitride or alloy containing at least one metal selected from the group consisting of Ni, Ti, Al, Cu, Pt, Fe, and Cr is more preferable. In particular, metal nitrides such as TiN and Cr ₂ N are preferable.

  Specific examples of the alloy include stainless steel (SUS), Inconel (registered trademark), Hastelloy (registered trademark), and other Fe—Cr alloys, Ni—Cr alloys, and the like. By using these alloys, higher potential resistance can be obtained.

  The short side size b of the flat conductive filler is preferably 1 to 100 nm, more preferably 1 to 50 nm, and still more preferably 1 to 20 nm. The long side size a of the flat conductive filler is, for example, 50 nm to 1 μm, and preferably 100 nm to 1 μm. The aspect ratio of the flat conductive filler is preferably 2 to 1000, more preferably 5 to 500, and still more preferably 50 to 300. Here, the aspect ratio of the flat conductive filler is a value represented by a / b. If the aspect ratio of the flat conductive filler is 2 or more, the maze effect becomes remarkable, and the permeation of the electrolyte and lithium ions can be effectively suppressed. Furthermore, the effect of reducing the resistance in the thickness direction of the current collector is high. In addition, if the aspect ratio is 1000 or less, the resistance in the surface direction of the current collector can be prevented from excessively decreasing and the lateral current can be prevented from flowing easily. Therefore, it is suitable for use as a current collector for bipolar batteries. It is.

  As shown in FIG. 2, the ion blocking layer 3 may further include an isotropic or acicular conductive filler 5 as a second conductive filler in addition to the flat conductive filler 4. Since the isotropic or acicular conductive filler 5 is disposed between the layers of the flat conductive filler 4, the thickness of the current collector can be increased by adding the isotropic or acicular conductive filler 5. It becomes easier to conduct in the vertical direction. For this reason, the resistance in the thickness direction of the current collector can be lowered more efficiently, and the cycle life of the battery can be improved. Here, the second conductive filler may include a conductive filler having an arbitrary shape excluding the shape of the flat conductive filler.

  The material of the second conductive filler may be the same as that of the first conductive filler. The average particle diameter of the second conductive filler is preferably 0.5 nm to 1 μm.

  The ratio of the amount used of the first conductive filler and the second conductive filler is not particularly limited, but is 1: 9 to 9: 1 (first conductive filler: second conductive filler). It is preferable that If the ratio of the amount used is in the above range, the resistance in the thickness direction of the current collector can be reduced more efficiently.

  As shown in FIG. 3, the ion blocking layer 3 further includes a binder 6 for holding the flat conductive filler 4 and / or the isotropic or acicular conductive filler 5 (when included). May be included. By using a binder, the contact between the conductive fillers can be improved, and the resistance in the thickness direction of the current collector can be reduced. In addition, the stress due to the swelling and shrinkage of the electrode can be relaxed, and the cycle life of the battery can be improved.

  Examples of the binder include polyvinylidene fluoride (PVDF), polyimide (PI), polytetrafluoroethylene (PTFE), SBR, and a synthetic rubber binder. However, it goes without saying that the binder is not limited to these. These binders may be used individually by 1 type, and may use 2 or more types together.

  The amount of the binder contained in the ion blocking layer is not particularly limited, but is preferably 5 to 30% by mass with respect to the total mass of the first conductive filler and the second conductive filler. If it is the said range, the effect of reducing the resistance of the collector in the thickness direction and the effect of improving the cycle life of the battery by relaxing the stress caused by the swelling and shrinkage of the electrode are high.

  The thickness of one layer of the ion blocking layer 3 of the present embodiment is not particularly limited, but is preferably 0.001 to 50 μm, more preferably 0.01 to 10 μm, particularly preferably 0.1 to 0.1 μm. 4 μm. If the thickness of the ion blocking layer 3 is 0.001 μm or more, the effect of blocking the penetration of lithium ions is high. Moreover, if it is 50 micrometers or less, it is preferable from a viewpoint of weight reduction. When a plurality of ion blocking layers are present, the thickness of at least one layer is preferably in the above range, and the thicknesses of all ion blocking layers are preferably in the above range.

  The thickness of the current collector 11 as a whole is not particularly limited, but it is preferably as thin as possible to increase the output density of the battery. In a bipolar battery, the current collector present between the positive electrode active material layer and the negative electrode active material layer may have a high electrical resistance in the direction parallel to the stacking direction, so the thickness of the current collector is reduced. It is possible. Specifically, the thickness of the entire current collector is preferably 0.1 to 300 μm, and more preferably 0.1 to 200 μm.

(Production method)
The method of producing a current collector by laminating a flat conductive filler on the surface of a conductive resin layer and an ion blocking layer whose long side direction is arranged in the surface direction of the resin layer is particularly limited. Not. An existing resin thin film or metal thin film deposition technique, lamination, or bonding technique can be used in appropriate combination.

  The method for obtaining the flat conductive filler is not particularly limited. A commercially available material may be used, or a commercially available material may be pulverized to a desired size by a pulverizer or the like. Alternatively, the flat conductive filler can be obtained by, for example, removing a sputtered isotropic material on a substrate and adjusting the size with a pulverizer or the like. The size and aspect ratio of the flat conductive filler can be confirmed with an electron microscope.

  The particles of the flat conductive filler can be laminated by being oriented in parallel with the surface of the conductive resin layer by, for example, sputtering. In addition, when an aerosol consisting of particulate conductive filler and carrier gas is sprayed onto the resin layer at high speed by the aerosol deposition method, particles deformed into a flat shape due to collision are deposited along the surface of the resin layer. To do. Alternatively, when a slurry containing a flat conductive filler, a binder, a solvent, or the like is applied to the conductive resin layer, the flat conductive filler particles are substantially parallel to each other and parallel to the surface of the resin layer. They are arranged in a line and stacked. When preparing the slurry, an isotropic or needle-like conductive filler may be further mixed.

  The current collector of the present embodiment has the following effects. That is, in a current collector including a resin layer having conductivity, an ion blocking layer in which the long side direction of a flat conductive filler is arranged in the surface direction of the resin layer is disposed on the surface of the resin layer. Thus, it becomes difficult for lithium ions to reach the conductive resin layer. By using such a current collector, a decrease in battery capacity due to occlusion of lithium ions can be suppressed.

<Electrode>
The current collector can be applied to both stacked (internal parallel connection type) batteries and bipolar (internal series connection type) batteries. Here, in a laminated battery, a positive electrode active material or a negative electrode active material is applied to a positive electrode current collector or a negative electrode current collector using a binder or the like to form an electrode (positive electrode or negative electrode). In the case of a bipolar battery, a positive electrode active material or the like is applied to one surface of the current collector, and a positive electrode active material layer is applied to the opposite surface, and a negative electrode active material layer is stacked. To construct a bipolar electrode. Here, in the bipolar battery, since the electric charge generated on the negative electrode side is directly supplied to the positive electrode on the opposite side of the current collector, the current flows in the direction perpendicular to the current collector (thickness direction). Directional (planar) flow is not required. Therefore, the current collector of the present embodiment is preferably used for a bipolar electrode.

  FIG. 4 shows the above-described secondary battery current collector 11, the positive electrode active material layer 13 formed on one surface of the secondary battery current collector 11, and the secondary battery current collector 11. It is the schematic of the bipolar electrode 23 containing the negative electrode active material layer 15 formed in the other surface of this.

  As shown in FIG. 4, in the current collector 11, the ion blocking layer is preferably formed on the surface of the conductive resin layer 2 on the side in contact with the negative electrode active material layer 15. Lithium ions in the electrolytic solution can enter the current collector 11 mainly from the joint surface between the negative electrode active material layer 15 and the current collector 11. Therefore, if the ion blocking layer 3 is formed on the negative electrode active material layer 15 side as shown in FIG. 4, the effect of preventing intrusion of lithium ions in the electrolytic solution is enhanced, and the capacity maintenance rate of the battery is improved. Is expensive.

  As shown in FIG. 4, when the bipolar electrode 23 is viewed from the negative electrode active material layer 15 side, it is preferable that the ion blocking layer 3 completely covers the region where the negative electrode active material layer 15 is formed. If the ion blocking layer 3 is disposed in a region that covers the region of the bonding surface between the negative electrode active material layer 15 and the conductive resin layer 2, the effect of preventing intrusion of lithium ions in the electrolytic solution is high.

  Hereinafter, other main components of the electrode will be described.

(Active material layer)
[Positive electrode active material layer]
The positive electrode active material layer 13 includes a positive electrode active material. The positive electrode active material has a composition that occludes ions during discharging and releases ions during charging. A preferable example is a lithium-transition metal composite oxide that is a composite oxide of a transition metal and lithium. Specifically, Li · Co-based composite oxide such as LiCoO _2, Li · Ni-based composite oxide such as LiNiO _2, Li · Mn-based composite oxide such as spinel LiMn ₂ O _4, Li · such LiFeO ₂ Fe-based composite oxides and those obtained by replacing some of these transition metals with other elements can be used. These lithium-transition metal composite oxides are excellent in reactivity and cycle characteristics, and are low-cost materials. Therefore, it is possible to form a battery having excellent output characteristics by using these materials for electrodes. In addition, examples of the positive electrode active material include transition metal oxides such as LiFePO ₄ and lithium phosphate compounds and sulfuric acid compounds; transition metal oxides such as V ₂ O ₅ , MnO ₂ , TiS ₂ , MoS ₂ , and MoO ₃ , and sulfides. Materials; PbO ₂ , AgO, NiOOH, etc. can also be used. The positive electrode active material may be used alone or in the form of a mixture of two or more.

  The average particle diameter of the positive electrode active material is not particularly limited, but is preferably 1 to 100 μm, more preferably 1 to 20 μm, from the viewpoint of increasing the capacity, reactivity, and cycle durability of the positive electrode active material. Within such a range, the secondary battery can suppress an increase in the internal resistance of the battery during charging and discharging under high output conditions, and can extract a sufficient current. When the positive electrode active material is secondary particles, it can be said that the average particle diameter of the primary particles constituting the secondary particles is preferably in the range of 10 nm to 1 μm. It is not limited to. However, it goes without saying that, depending on the manufacturing method, the positive electrode active material may not be a secondary particle formed by aggregation, agglomeration, or the like. As the particle diameter of the positive electrode active material and the particle diameter of the primary particles, a median diameter obtained by using a laser diffraction method can be used. The shape of the positive electrode active material varies depending on the type and manufacturing method, and examples thereof include a spherical shape (powdered shape), a plate shape, a needle shape, a column shape, and a square shape, but are not limited thereto. Any shape can be used without any problems. Preferably, an optimal shape that can improve battery characteristics such as charge / discharge characteristics is appropriately selected.

[Negative electrode active material layer]
The negative electrode active material layer 15 includes a negative electrode active material. The negative electrode active material has a composition capable of releasing ions during discharge and storing ions during charging. The negative electrode active material is not particularly limited as long as it can reversibly occlude and release lithium. Examples of the negative electrode active material include metals such as Si and Sn, TiO, Ti ₂ O ₃ , TiO ₂ , or Metal oxides such as SiO ₂ , SiO, SnO ₂ , complex oxides of lithium and transition metals such as Li _4/3 Ti _5/3 O ₄ or Li ₇ MnN, Li—Pb alloys, Li—Al alloys , Li, or carbon materials such as natural graphite, artificial graphite, carbon black, activated carbon, carbon fiber, coke, soft carbon, or hard carbon. Moreover, it is preferable that a negative electrode active material contains the element alloyed with lithium. By using an element that forms an alloy with lithium, it is possible to obtain a battery having a high capacity and an excellent output characteristic having a higher energy density than that of a conventional carbon-based material. The negative electrode active material may be used alone or in the form of a mixture of two or more.

  The element alloying with lithium is not limited to the following, but specifically, Si, Ge, Sn, Pb, Al, In, Zn, H, Ca, Sr, Ba, Ru, Rh, Ir, Pd, Pt, Ag, Au, Cd, Hg, Ga, Tl, C, N, Sb, Bi, O, S, Se, Te, Cl, and the like. Among these, from the viewpoint of configuring a battery having excellent capacity and energy density, at least one selected from the group consisting of carbon materials and / or Si, Ge, Sn, Pb, Al, In, and Zn. It is preferable that an element is included, and it is particularly preferable that an element of a carbon material, Si, or Sn is included. These may be used alone or in combination of two or more.

  The average particle size of the negative electrode active material is not particularly limited, but is preferably 1 to 100 μm, more preferably 1 to 20 μm from the viewpoint of increasing the capacity, reactivity, and cycle durability of the negative electrode active material. Within such a range, the secondary battery can suppress an increase in the internal resistance of the battery during charging and discharging under high output conditions, and can extract a sufficient current. In addition, when the negative electrode active material is secondary particles, it can be said that the average particle diameter of primary particles constituting the secondary particles is desirably in the range of 10 nm to 1 μm. It is not limited to. However, it goes without saying that, depending on the manufacturing method, the negative electrode active material may not be a secondary particle formed by aggregation, lump or the like. As the particle diameter of the negative electrode active material and the particle diameter of the primary particles, a median diameter obtained by using a laser diffraction method can be used. The shape of the negative electrode active material varies depending on the type and manufacturing method, and examples thereof include a spherical shape (powdered shape), a plate shape, a needle shape, a column shape, and a square shape, but are not limited thereto. Any shape can be used without any problems. Preferably, an optimal shape that can improve battery characteristics such as charge / discharge characteristics is appropriately selected.

  The active material layers (13, 15) may contain other materials if necessary. For example, a conductive aid, a binder, and the like can be included. When an ion conductive polymer is included, a polymerization initiator for polymerizing the polymer may be included.

  A conductive support agent means the additive mix | blended in order to improve the electroconductivity of an active material layer. Examples of the conductive aid include carbon powders such as acetylene black, carbon black, ketjen black, and graphite, various carbon fibers such as vapor grown carbon fiber (VGCF; registered trademark), expanded graphite, and the like. However, it goes without saying that the conductive aid is not limited to these.

  Examples of the binder include polyvinylidene fluoride (PVDF), PI, PTFE, SBR, and a synthetic rubber binder. However, it goes without saying that the binder is not limited to these. When the binder and the matrix polymer used as the gel electrolyte are the same, it is not necessary to use a binder.

The compounding ratio of the components contained in the active material layer is not particularly limited. The blending ratio can be adjusted by appropriately referring to known knowledge about lithium ion secondary batteries. The thickness of the active material layer is not particularly limited, and conventionally known knowledge about the lithium ion secondary battery can be appropriately referred to. As an example, the thickness of the active material layer is preferably about 10 to 100 μm, and more preferably 20 to 50 μm. If the active material layer is about 10 μm or more, the battery capacity can be sufficiently secured. On the other hand, when the active material layer is about 100 μm or less, it is possible to suppress the occurrence of the problem of an increase in internal resistance due to the difficulty of diffusing Li ⁺ into the electrode deep part (current collector side).

  The method for forming the positive electrode active material layer (or the negative electrode active material layer) on the current collector surface is not particularly limited, and known methods can be used in the same manner. For example, as described above, a positive electrode active material (or negative electrode active material), and if necessary, an electrolyte salt, a conductive additive, and a binder are dispersed and dissolved in an appropriate solvent to obtain a positive electrode active material slurry ( Alternatively, a negative electrode active material slurry) is prepared. This is applied onto a current collector, dried to remove the solvent, and then pressed to form a positive electrode active material layer (or negative electrode active material layer) on the current collector. In this case, the solvent is not particularly limited, and N-methyl-2-pyrrolidone (NMP), dimethylformamide, dimethylacetamide, methylformamide, cyclohexane, hexane, water and the like can be used. When adopting polyvinylidene fluoride (PVDF) as the binder, NMP is preferably used as a solvent.

  In the above method, the positive electrode active material slurry (or the negative electrode active material slurry) is applied onto the current collector, dried, and then pressed. Specific means and press conditions for the press treatment are not particularly limited, and can be appropriately adjusted so that the porosity of the positive electrode active material layer (or the negative electrode active material layer) after the press treatment becomes a desired value. Specific examples of the press process include a hot press machine and a calendar roll press machine. Also, the pressing conditions (temperature, pressure, etc.) are not particularly limited, and conventionally known knowledge can be referred to as appropriate.

  According to the electrode of the present embodiment, since the ion blocking layer is disposed on the surface of the resin layer and includes a flat conductive filler, the long side direction of which is arranged in the surface direction of the resin layer, lithium ions are It is necessary to reach between the flat conductive fillers to reach the resin layer. As a result, penetration and occlusion of lithium ions into the resin layer are prevented.

<Bipolar type secondary battery>
FIG. 5 is a cross-sectional view schematically showing the overall structure of a bipolar secondary battery according to an embodiment of the present invention. The bipolar secondary battery 10 of this embodiment shown in FIG. 5 has a structure in which a substantially rectangular power generation element 21 in which a charge / discharge reaction actually proceeds is sealed inside a laminate film 29 that is a battery exterior material. .

  As shown in FIG. 5, in the power generation element 21 of the bipolar secondary battery 10 of the present embodiment, a positive electrode active material layer 13 that is electrically coupled to one surface of the current collector 11 is formed. And a plurality of bipolar electrodes 23 having a negative electrode active material layer 15 electrically coupled to the opposite surface. Each bipolar electrode 23 is laminated via the electrolyte layer 17 to form the power generation element 21. The electrolyte layer 17 has a configuration in which an electrolyte is held at the center in the surface direction of a separator as a base material. At this time, the positive electrode active material layer 13 of one bipolar electrode 23 and the negative electrode active material layer 15 of another bipolar electrode 23 adjacent to the one bipolar electrode 23 face each other through the electrolyte layer 17. The bipolar electrodes 23 and the electrolyte layers 17 are alternately stacked. That is, the electrolyte layer 17 is interposed between the positive electrode active material layer 13 of one bipolar electrode 23 and the negative electrode active material layer 15 of another bipolar electrode 23 adjacent to the one bipolar electrode 23. ing.

  The adjacent positive electrode active material layer 13, electrolyte layer 17, and negative electrode active material layer 15 constitute one unit cell layer 19. Therefore, it can be said that the bipolar secondary battery 10 has a configuration in which the single battery layers 19 are stacked. Further, for the purpose of preventing liquid junction due to leakage of the electrolytic solution from the electrolyte layer 17, a seal portion (insulating layer) 31 is disposed on the outer peripheral portion of the unit cell layer 19. A positive electrode active material layer 13 is formed only on one side of the positive electrode outermost layer current collector 11 a located in the outermost layer of the power generation element 21. The negative electrode active material layer 15 is formed only on one surface of the outermost current collector 11b on the negative electrode side located in the outermost layer of the power generation element 21.

  Furthermore, in the bipolar secondary battery 10 shown in FIG. 5, the positive electrode current collector plate 25 is disposed adjacent to the outermost layer current collector 11a on the positive electrode side, and this is extended from the laminate film 29 that is a battery exterior material. Derived. On the other hand, the negative electrode current collector plate 27 is disposed so as to be adjacent to the outermost layer current collector 11 b on the negative electrode side, and is similarly extended and led out from the laminate film 29.

  In the bipolar secondary battery 10 shown in FIG. 5, the seal portion 31 is usually provided around each single cell layer 19. The purpose of the seal portion 31 is to prevent the adjacent current collectors 11 in the battery from coming into contact with each other and a short circuit caused by a slight irregularity at the end of the unit cell layer 19 in the power generation element 21. Provided. By installing such a seal portion 31, long-term reliability and safety are ensured, and a high-quality bipolar secondary battery 10 can be provided.

  Note that the number of stacks of the unit cell layers 19 is adjusted according to a desired voltage. Further, in the bipolar secondary battery 10, the number of stacking of the single battery layers 19 may be reduced if a sufficient output can be secured even if the thickness of the battery is made as thin as possible. Even in the bipolar secondary battery 10, in order to prevent external impact and environmental degradation during use, the power generation element 21 is sealed under reduced pressure in a laminate film 29 that is a battery exterior material, and the positive electrode current collector plate 25 and the negative electrode current collector 25. A structure in which the electric plate 27 is taken out of the laminate film 29 is preferable. Hereinafter, main components of the bipolar secondary battery of this embodiment will be described.

[Electrolyte layer]
There is no restriction | limiting in particular in the electrolyte which comprises an electrolyte layer, Polymer electrolytes, such as a liquid electrolyte and a polymer gel electrolyte and a polymer solid electrolyte, can be used suitably.

  The liquid electrolyte is obtained by dissolving a lithium salt as a supporting salt in a solvent. Examples of the solvent include dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), ethyl methyl carbonate (EMC), methyl propionate (MP), methyl acetate (MA), and methyl formate (MF). 4-methyldioxolane (4MeDOL), dioxolane (DOL), 2-methyltetrahydrofuran (2MeTHF), tetrahydrofuran (THF), dimethoxyethane (DME), ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC) , And γ-butyrolactone (GBL). These solvents may be used alone or as a mixture of two or more.

As the supporting salt (lithium salt) is not particularly _{limited, LiPF 6, LiBF 4, LiClO} 4, LiAsF 6, LiTaF 6, LiSbF 6, LiAlCl 4, Li 2 B 10 Cl 10, LiI, LiBr, LiCl Inorganic acid anion salts such as LiAlCl, LiHF ₂ , LiSCN, LiCF ₃ SO ₃ , Li (CF ₃ SO ₂ ) ₂ N, LiBOB (lithium bisoxide borate), LiBETI (lithium bis (perfluoroethylenesulfonylimide); And organic acid anion salts such as Li (C ₂ F ₅ SO ₂ ) ₂ N). These electrolyte salts may be used alone or in the form of a mixture of two or more.

On the other hand, the polymer electrolyte is classified into a gel electrolyte containing an electrolytic solution and a polymer solid electrolyte containing no electrolytic solution. The gel electrolyte has a configuration in which the liquid electrolyte is injected into a matrix polymer having Li ⁺ conductivity. As the matrix polymer having Li ⁺ conductivity, for example, a polymer having polyethylene oxide in the main chain or side chain (PEO), a polymer having polypropylene oxide in the main chain or side chain (PPO), polyethylene glycol (PEG), poly Acrylonitrile (PAN), polymethacrylic acid ester, polyvinylidene fluoride (PVDF), copolymer of polyvinylidene fluoride and hexafluoropropylene (PVDF-HFP), polyacrylonitrile (PAN), poly (methyl acrylate) (PMA), poly (Methyl methacrylate) (PMMA) etc. are mentioned. In addition, mixtures of the above-described polymers, modified products, derivatives, random copolymers, alternating copolymers, graft copolymers, block copolymers, and the like can also be used. Among these, it is desirable to use PEO, PPO and their copolymers, PVDF, PVDF-HFP. In such a matrix polymer, an electrolyte salt such as a lithium salt can be well dissolved.

  In addition, when an electrolyte layer is comprised from a liquid electrolyte or a gel electrolyte, you may use a separator for an electrolyte layer. Specific examples of the separator include a microporous film made of polyolefin such as polyethylene and polypropylene, hydrocarbon such as polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP), glass fiber, and the like.

  The polymer solid electrolyte has a structure in which a supporting salt (lithium salt) is dissolved in the matrix polymer, and does not include an organic solvent that is a plasticizer. Therefore, when the electrolyte layer is composed of a polymer solid electrolyte, there is no fear of liquid leakage from the battery, and the battery reliability can be improved.

  A matrix polymer of a polymer gel electrolyte or a polymer solid electrolyte can exhibit excellent mechanical strength by forming a crosslinked structure. In order to form a crosslinked structure, thermal polymerization, ultraviolet polymerization, radiation polymerization, electron beam polymerization, etc. are performed on a polymerizable polymer (for example, PEO or PPO) for forming a polymer electrolyte, using an appropriate polymerization initiator. A polymerization treatment may be performed. In addition, the said electrolyte may be contained in the active material layer of an electrode.

[Seal part]
The seal portion (insulating layer) has a function of preventing contact between current collectors and a short circuit at the end of the single cell layer. As a material constituting the seal portion, any material having insulating properties, sealability against falling off of solid electrolyte, sealability against moisture permeation from the outside (sealing property), heat resistance under battery operating temperature, etc. Good. For example, urethane resin, epoxy resin, polyethylene resin, polypropylene resin, polyimide resin, rubber and the like can be used. Of these, polyethylene resin and polypropylene resin are preferably used as the constituent material of the insulating layer from the viewpoints of corrosion resistance, chemical resistance, ease of production (film forming property), economy, and the like.

[Battery exterior materials]
As the battery exterior material, a conventionally known metal can case can be used, and a bag-like case using a laminate film containing aluminum that can cover the power generation element can be used. For example, a laminate film having a three-layer structure in which polypropylene, aluminum, and nylon are laminated in this order can be used as the laminate film, but the laminate film is not limited thereto. In this embodiment, a laminate film that is excellent in high output and cooling performance and can be suitably used for a battery for large equipment such as for EV and HEV is desirable.

  According to the bipolar secondary battery 10 of this embodiment, in order for lithium ions to reach the inside of the resin layer, it is necessary to wrap around between the flat conductive fillers (maze effect). Infiltration and occlusion into the resin layer are prevented. Thus, by preventing penetration and occlusion of lithium ions into the resin layer, a decrease in battery capacity associated with this can be suppressed.

  The secondary battery described above is used as a power source for driving a vehicle or an auxiliary power source that requires a high volume energy density and a high volume output density as a large capacity power source for an electric vehicle, a hybrid electric vehicle, a fuel cell vehicle, a hybrid fuel cell auto company, etc. It can be suitably used.

  Hereinafter, the effects of the present invention will be described using examples and comparative examples. However, the technical scope of the present invention is not limited only to the following examples.

<Example 1>
A film-like resin layer having a thickness of 50 μm, in which 5% by mass of ketjen black (average primary particle size: 35 nm) as a conductive filler is dispersed with respect to 100% by mass of polyimide (PI) as a polymer material. It was prepared using the melt casting method.

On one surface of this resin layer, as an ion blocking layer, flat titanium nitride (TiN) particles that are flat conductive fillers (average length of long sides: 50 nm, average length of short sides: 10 nm, average A current ratio of 5) was formed to a thickness of 300 nm by sputtering. As sputtering conditions, argon gas 1 × 10 ⁻⁴ Pa was introduced, and a film was formed at a temperature of about 200 ° C. and a rate of 2 nm / second. The above-mentioned flat titanium nitride particles were used by adjusting the size with a pulverizer by once sputtering and peeling the isotropic particles onto the glass substrate.

<Example 2>
A battery was fabricated in the same manner as in Example 1 described above, except that ion blocking layers were fabricated on both sides of the resin layer.

<Example 3>
Current collection by the same method as in Example 1 except that flat titanium nitride particles having an average long side length of 50 nm, an average short side length of 5 nm, and an average aspect ratio of 10 were used. The body was made.

<Example 4>
Flat titanium nitride particles (average length of long side: 600 nm, average length of short side: 2 nm, average aspect ratio: 300) and polyvinylidene fluoride (PVDF) as a binder are mixed at a mass ratio of 9: 1. did. Further, N-methyl-2-pyrrolidone (NMP) as a solvent was added and dissolved so that the solid content was 75% by mass. Thereafter, a current collector was produced in the same manner as in Example 1 except that the ion blocking layer was produced by coating the conductive resin film on one side with a thickness of 3 μm.

<Example 5>
Flat titanium nitride particles (average length of long side: 100 nm, average length of short side: 2 nm, average aspect ratio: 50) and isotropic titanium nitride particles (manufactured by Nippon Metal Co., Ltd., average particle size: 0) .7 to 0.84 nm, average aspect ratio: 1.2) and PVDF were mixed and used. The mixing ratio (mass ratio) was 8: 1: 1 (flat titanium nitride particles: isotropic titanium nitride particles: PVDF). The current collector was prepared by the same method as in Example 4 described above under other conditions.

<Example 6>
Flat titanium nitride particles (average length of long sides: 100 nm, average length of short sides: 2 nm, average aspect ratio: 50) and isotropic titanium nitride particles (average particle size: 0.7 to 0.84 nm) Average aspect ratio: 1.2) and PVDF were mixed at a mass ratio of 3: 6: 1. The current collector was prepared by the same method as in Example 4 described above under other conditions.

<Example 7>
Except for using flat chrome nitride (Cr ₂ N) particles having an average long side length of 50 nm, an average short side length of 5 nm, and an average aspect ratio of 10 as the flat conductive filler. A current collector was produced in the same manner as in Example 1 described above. The above-mentioned flat chromium nitride particles were used after the isotropic particles were once sputtered off the glass substrate and the size was adjusted with a pulverizer.

<Comparative Example 1>
Only the above resin layer was used as a current collector without providing an ion blocking layer.

<Comparative example 2>
An isotropic titanium nitride (TiN) particle having an average particle diameter of 0.7 to 0.84 nm and an average aspect ratio of 1.2 is formed on one surface of the resin layer to a thickness of 30 nm by a sputtering method. A battery was fabricated in the same manner as in Example 1 except that was stacked.

<Production of battery>
85% by mass of LiNi ₂ O ₄ as a positive electrode active material, 5% by mass of acetylene black as a conductive additive, 10% by mass of PVDF as a binder, and an appropriate amount of NMP as a slurry viscosity adjusting solvent were mixed to prepare a positive electrode active material slurry.

  On the other hand, 90% by mass of graphite (MCMB) as a negative electrode active material, 10% by mass of PVDF as a binder, and an appropriate amount of NMP as a slurry viscosity adjusting solvent were mixed to prepare a negative electrode active material slurry.

  The negative electrode active material slurry was applied to the surface of the current collector prepared in each Example and Comparative Example on the side where the ion blocking layer was formed, and dried at 80 ° C. to form a coating film, thereby preparing a negative electrode. In addition, the positive electrode active material slurry is applied to the surface of the other current collector that is not formed with the ion blocking layer, and dried at 80 ° C. to form a coating film, and then pressed. A positive electrode was produced. The thicknesses of the positive electrode active material layer and the negative electrode active material layer were 80 μm and 60 μm, respectively. The negative electrode active material slurry was applied to the back surface of each of the positive electrode and the negative electrode prepared above, and a current collector plate was attached by overlapping the mesh metal foil.

As an electrolytic solution, a solution was prepared by dissolving LiPF ₆ as a lithium salt at a concentration of 1 mol / L in an equal volume mixture of propylene carbonate (PC) and ethylene carbonate (EC).

  The positive electrode and the negative electrode produced above were laminated so that the positive electrode active material layer and the negative electrode active material layer faced each other with a separator interposed therebetween, and a laminate was produced. Three sides of this laminate were heat-sealed using a sealing agent to form a bag. Next, the electrolyte solution was poured from the remaining open side, and the remaining side was vacuum-sealed to produce a single-layer battery.

<Measurement of discharge capacity maintenance rate>
The battery produced by the above method was degassed after charging at 0.1 C (8 mA) in an atmosphere at 25 ° C., capacity was confirmed at 1 C, and then cycle evaluation was performed at 1 C at 45 ° C. Specifically, these batteries are charged at a constant current (CC) up to 4.2 V with a current of 1 C (80 mA), then charged at a constant voltage (CV) and charged for a total of 2.5 hours, up to 2.5 V Up to 30 cycles of constant current (CC) discharge were performed. The percentage (%) of the discharge capacity at the 30th cycle with respect to the first discharge capacity after degassing was taken as the capacity maintenance rate. The results are shown in Table 1.

<Measurement of direct resistance>
Silver paste was applied to both sides of the current collectors prepared in Examples 1 to 7 and Comparative Examples 1 and 2, and dried to prepare an evaluation sample. Cut the sample into a 20 mm diameter, sandwich it in a 20 mm diameter gold foil (thickness: 100 μm), and use a resistance measuring device (TER-2000SS, manufactured by ULVAC-RIKO), in the film thickness direction, 4 terminals (current and voltage probes are separate) Was measured by a constant method. The measurement pressure was 0.1 to 3.0 MPa, and the measurement temperature was room temperature. The results are shown in Table 1.

  As shown in Table 1, the batteries using the current collectors of Examples 1 to 7 each having an ion blocking layer containing a flat conductive filler were compared to Comparative Example 1 and the isotropic conductive layer including no ion blocking layer. Compared to the battery using the current collector of Comparative Example 2 using only the filler, the capacity retention rate of the battery is improved. This is presumably because a labyrinth effect is produced and the solvent blocking property of the ion blocking layer is improved by laminating an ion blocking layer in which flat conductive fillers are arranged in the surface direction of the resin layer. In addition, from the comparison of Examples 1, 3, and 4, the labyrinth effect becomes more prominent as the aspect ratio of the flat conductive filler increases, the solvent blocking property is improved, and the capacity retention rate (cycle characteristics) is improved. To do.

  Moreover, when a binder is used like Examples 4-6, since the contact of the conductive fillers contained in an ion interruption layer improves, the effect of reduction of a surface resistance is large. Furthermore, as in Examples 5 and 6, by adding an isotropic conductive filler at an appropriate ratio, the direct resistance is further reduced. This is considered to be because conduction is easily achieved in the thickness direction by arranging isotropic conductive fillers between the flat conductive fillers arranged in layers in the plane direction. It is considered that such reduction of the direct resistance improves current collection efficiency and improves cycle characteristics.

2 resin layer,
3 ion blocking layer,
4 flat conductive filler (first conductive filler),
5 isotropic or acicular conductive filler (second conductive filler),
6 Binder,
10 Bipolar secondary battery,
11 Current collector,
11a The outermost layer current collector on the positive electrode side,
11b The outermost layer current collector on the negative electrode side,
13 positive electrode active material layer,
15 negative electrode active material layer,
17 electrolyte layer,
19 cell layer,
21 power generation elements,
23 Bipolar electrode,
25 positive current collector,
27 negative current collector,
29 Laminated film,
31 Seal part.

Claims (6)

A resin layer having electrical conductivity;
An ion blocking layer disposed on the surface of the resin layer, and a current collector for a secondary battery,
The ion blocking layer includes a flat conductive filler, and the flat conductive filler is made of Ni, Ti, Al, Cu, Pt, Fe, Cr, Sn, Zn, In, Sb, and K. A current collector for a secondary battery , which is a metal nitride containing at least one metal selected from the group consisting of :   The current collector for a secondary battery according to claim 1, wherein the ion blocking layer further includes an isotropic or acicular conductive filler. Before SL isotropic shape or needle-like conductive filler over a metal, alloy, metal carbides, metal nitrides, metal oxides, metal borides, metal sulfides, diamond-like carbon, glassy carbon, and the group consisting of ceramics The current collector for a secondary battery according to claim 2 , wherein the current collector is at least one selected from the group consisting of: The ion blocking layer further comprises a binder, current collector for a secondary battery according to any one of claims 1 to 3. A current collector for a secondary battery according to any one of claims 1 to 4,
A positive electrode active material layer formed on one surface of the current collector for the secondary battery;
A negative electrode active material layer formed on the other surface of the current collector for the secondary battery, and a bipolar electrode comprising:
The bipolar electrode in which the ion blocking layer of the current collector for the secondary battery is disposed on the surface of the conductive resin layer on the negative electrode active material layer side.   A bipolar battery comprising the bipolar electrode according to claim 5.

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